Cystic fibrosis is a genetic disease that affects many organs and appears to reflect a generalized epithelial dysfunction. Cystic fibrosis is characterized by abnormal fluid and solute balance across the epithelia of several organs. The lung is usually the critical organ because thickened airway liquid appears to contribute to recurrent infection with progressive loss of ventilatory function. Cystic fibrosis is characterized by abnormalities that render mucus excessively thick, dehydrated and tenacious, qualities that lead to retention of material in the airways. Secretions of this nature are difficult to clear from airway surfaces and build up to obstruct airway lumens. This obstuction produces substantial impairments in respiration. Whereas the etiology of abnormal secretions is best understood in cystic fibrosis, retained secretions are important contributors to other lung diseases, e.g., asthma and chronic obstructive pulmonary disease.
The therapeutic goal in cystic fibrosis and other lung diseases is to remove retained secretions from the lung. Treatment of such pulmonary manifestations includes liquifying mucus and minimizing its formation, preventing obstruction and controlling infection. At present, only physical means (e.g., physical therapy including breathing exercises) are of any effectiveness in accomplishing this goal.